Other versions exist on this site from various publications. This one is from the Radio Electronics Experimenter from 1990. The bargraph circuit uses the UAA170.
With the values of the components indicated, this timer controls intervals from a few seconds to a...
This 80's circuit uses a light-sensitive SCR or LASCR and a one-sided silicon switch SUS, uncommon...
This circuit, found in ancient US documentation, allows you to switch the antenna from the...